Bus duct plug mounting device with improved interlocking means



' April 4, 1967 R s. DAVIS 3,312,872

BUS Duc PLu MOUNTING DEVICE WITH 7 IMPROVED INTERLOCKING MEANS FiledAug. 30, 1965 2 Sheets-Sheet 1 NIH I N VEN TOR.

A ril 4, 1967 Filed Aug. :50, 1965.

R. S. DAVIS BUS DUCT PLUG MOUNTING DEVICE WITH IMPROVED INTERLOCKINGMEANS 2 Sheets-Sheet 2 United States Patent BUS DUCT PLUG MOUNTINGDEVICE WITH IMPROVED INTERLOCKING MEANS Russell S. Davis, Detroit, Mich,assignor to I-T-E (Zircuit Breaker Company, Philadelphia, Pa., 2corporation of Pennsylvania Filed Aug. 30, 1965, Ser. No. 483,639 9Claims. (Cl. 317-119) This invention relates to bus duct plugs ingeneral and more particularly relates to novel means for mounting of theplug to a duct.

Bus duct is usually installed at a considerable height above floor levelso that it is necesary for an electrician to use a' ladder in order tomount and dismount power tapping plugs to the duct. Plugs of relativelymodest current ratings are of such great bulk and/ or great weight thatan electrician must use both of his hands to safely handle such plugs.Under these circumstances it is very d fiicuIt for an electrician tosupport the plug with one hand while attempting to insert a fasteningscrew through a plug housing aperture into a threaded aperture in theduct casing.

The basic screw type securement means was character istic of earlyconstructions. Because of the many difficulties encountered with thistype of construction the prior art progressed by providing elongatedslots with enlarged ends to cooperate with fastening screws with theheads of the fastening screws being insertable into the enlarged endsbut being too large to pass through the slots. This solution isundesirable in that it requires that holes be formed in the duct casingand the entire plug weight I must be supported by the electrician whilehe lines up the plug screws with the enlarged ends. Another prior artattempt at solution of the problem was a fastening means which extendedcompletely over the top of the duct housing. But this latter fasteningmeans interfered with the mounting of a plug on the opposite side of theduct. Snap-onfastening means have been tried but they are not positiveor safe and the snap-on clamping members are easily distorted so thatthis solution is totally unsuited for large size plugs. I

T'heinstant invention overcomes the disadvantages of prior art byproviding hook means which engage external formations of the ducthousing. These hook means are permanently mounted to the plug so as tobe pivotable and slidable with respect to the plug. Pressure applyingmeans acting between the hook means and plug housing drawthe-hook tipsinto firm holding engagement with the duct housing to positively securethe plug to the duct. These hook means are provided at both the upperand lower edges of the plug housing. A blocking means secured to theplug housing limits or essentially prevents pivotable movement oftheupper hook means so that this hook means may act as a fixed pivot forthe plugrelative to the duct housing during the initial mounting of theplug. g Accordingly, a primary object of the instant invention is toprovide a novel means for the securement of busduct plugs to a bus ductwith this means providing a positive securement requiring relativelylittle time to make.

Another object is to provide a fastening means of this type which willnot interfere with the mounting of a plug on the opposite side of theduct.

Still another object is to provide a fastening means of this type whichis permanently mounted to the plug and does not require the handling ofseparate members.

A further object is to provide a fastening means of this type which doesnot require that special apertures or indentations formation be formedin the duct housing.

These as Well as other objects of this invention will be- 3,3l2,872Patented Apr. 4, 1967 come readily apparent after reading the followingdescription of the accompanying drawings in which:

FIGURE 1 is a perspective of a bus duct plug including the novelfastening means of the instant invention.

FIGURE 2 is a fragmentary rear elevation showing the plug of FIGURE Imounted to a bus duct.

FIGURES 3A and 3B are an end and bottom view, respectively, of thestructure shown in FIGURE 2 looking in the direction of arrows 3A, 3Aand 3B, 3B respectively, of FIGURE 2.

FIGURE 4 is a side elevation showing various positions that the mountinghook may assume.

FIGURE 5 is a side elevation of one of the mounting hooks.

FIGURES 6 and 7 are elevations of the mounting hook looking in thedirection of arrows 6-6 and 7-7, respectively, of FIGURE 5.

Now referring to the figures. Bus duct plug 10 is provided withrectangular house 19 having front face 11 with an aperture 12 therein.Bus bar engaging plug in fingers 13, 14, 15, 16, maintained in spacedinsulating relationship by insulator block 17 within housing 19, extendthrough aperture 12 forwardly of front wall 11 to engage the bus bars(not shown) of bus duct 50 (FIGURE 2) when plug 10 is mounted thereto.Plug 10 also includes circuit interrupting means, in this case fuses(not shown), mounted within housing 19.

In order to mount plug 10 to bus duct casing 51, plug 10 is providedwith upper 21, 25 and lower 22, 26 hook members mounted to plug housingend walls 23 and 24 (FIGURESA) in a manner to be hereinafter explained.Since each of the hook members 21, 22, 25 and 26 is of identicalconstruction and is mounted in the same manner, for the sake of brevityand without loss of clarity, only hook member 25 and its mounting willbe described in detail with particular reference to FIGURES 5 through 7Member 25 is generally L-shaped having elongated leg 31 extending atright angles to elongated leg 32. The end of leg 31 remote from leg 32is turned inwardly toward leg 32 to provide hook tip 33 with open mouth34 facing leg 32. Spaced parallel ears 35, 36 extend from opposite edgesof leg 32 away from hook tip 33 and lie in planes generallyperpendicular to the longitudinal axis of legs 31; Bars 35, 36 areprovided with aligned elongated apertures 35a, 36a, respectively,extending generaly parallel to the longitudinal axis of web 31. Slots35a, 36a are formed at a point near the center of leg 32. Threadedaperture 37 is formed in leg 32 at a position near the-end of leg 32remote from leg 31.

' One leg 42 of angle 40 is afiixed to end wall 24 in abutment therewithwhile the other leg 41 of angle 40 is positioned in the same plane asfront wall 11. Pin 44, having an enlarged slotted head at one end andthreads at the other end, extends through aligned apertures 35a,

36a and is received by aligned threaded apertures (not shown) in leg 42and end wall 24. Pin-slot means 44,- 35a, 36a guides member 25forpivotal and linear motion with respect to plug housing 19.

Clampingscre'w 46 is mounted in aperture 37 with the head of screw 46being positioned between ears 35, 36 and the free end of screw 46 beingengageable with leg 41, for a reason to be hereinafter explained. Screw48 is received by aligned threaded apertures (not shown) in leg 42 andside wall 24 with the head of screw 48 being positioned in the plane ofear 36 adjacent to the edge 36b of ear 36 which extends generallyparallel to the longitudinal axis of leg 31. Screw 48 is so positionedrelative to pin 44 and edge 36b that member 25 is restricted to motionessentially parallel to the axis of aligned slots -35a, 36a for a reasonwhich will hereinafter be explained. It is noted that screws similar to48 are not provided for hook members 21, 22 and 26 so that these membersmay pivot about pin 44 to the dotted line position A of FIGURE 4.

In order to mount plug to casing 51 of bus duct 50 (FIGURES 2, 3A and3B) hook member is moved to the dotted line position B of FIGURE 4 andscrews 46 of hook members 22 and 26 are backed out so that thesemembers, being acted upon by gravity, will assume positionscorresponding to the dotted line position A of FIGURE 4. The hook tip ofmember 25 is placed over the upward protrusion 55 along the upper edgeof duct casing 51. Plug 10 is then moved longitudinally along bus duct50 until interlock finger 54 (FIGURE 1) is aligned with a cooperatingaperture (not shown) in duct casing 51. An access aperture cover (notshown) of duct 50 is then moved to open position permitting interlockfinger 54 to move into duct casing 51 as plug 10 pivots about the hooktip of member 25 to a position where front wall 11 is parallel to theconfronting wall of duct casing, 51. In this position, plug-in fingers13, 14, 15, 16 electrically engage individual bus bars (not shown) ofbus duct 50 and the hook tip of member 21 engages protrusion 55. Thefunction and operation of interlock finger 54 is shown and described indetail in the I. B. Cataldo et al. US. Patent 3,048,672 issued Aug. 7,1962, for a Safety Bus Duct Plug.

At this point plug 10 requires no further support from the installingelectrician. Screw 46 mounted to hook member 25 is now tightened to drawmember 25 to a position corresponding to the dotted line position C ofFIGURE 4. Hook member 21 is moved to, and maintained in, holdingposition by tightening its screw 46. One and then the other of hookmembers 22 and 26 is pivoted upwardly with the hook tip thereof movingforward of downward protrusion 56 along the lower edge of duct casing 51and is then moved to clamping position by rotating screw 46 of theparticular hook member 22 or 26 until this member reaches its holdingposition (corresponding to position C of FIGURE 4). Now the position ofthe particular screw 46 prevents either linear or pivotal movement ofmembers 22 and 26.

Thus, it is seen that the instant invention provides a novel means forpositively securing a bus duct plug to a bus duct casing. The means areso constructed that all of the necessary elements are permanentlyafiixed to the plug and no special apertures or indentations arerequired in the bus duct casing.

Although there has been described a preferred em bodiment of this novelinvention, many variations and modifications will 'now be apparent tothose skilled in the art. Therefore, this invention is to be limited,not by the specific disclosure herein, but only the appending claims.

The embodiments of the invention in which an exclusive privilege orproperty is claimed are defined as follows:

1. A bust duct plug comprising a plurality of bus bar engaging fingers;a housing to which said fingers are secured; said housing having a frontwall with an aperture through which said fingers extend forwardly ofsaid front wall; said housing also having first and second end wallsextending rearwardly from opposite first and second edges, respectively,of said front wall; mounting means for securing said plug to a bus ductcasing; said mounting means including upper and lower portions havingindividual open hook portions facing one another and projecting forwardof said front wall; said lower portion including a member having one ofsaid hook portions at one end thereof, pin-slot means mounting the otherend of said member to said first end wall; said pin-slot means defininga pivot for said member extending generally parallel to said front wall;said pin-slot means also defining means guiding said member for linearmovement of said one hook portion toward and away from said front wall;an adjustable force applying means acting between said housing andsecond member for operating the latter to a holding position and holdingthe member at said position.

2. A plug as set forth in claim 1 in which said pinslot means includesan elongated slot in said member and a pin mounted to said wall andextending into said slot.

3. A plug as set forth in claim 2 in which the force applying means ismounted to said member.

4. A plug as set forth in claim 3 in which the force applying meanscomprising ascrew positioned to the rear of said slot.

5. A plug as set forth in claim 1 in which said member includes a firstsection and a second section at one end of said first section; said hookportion of said member positioned at the end of said first sectionremote from said second section; said hook portion having an open sidefacing said second section.

6. A plug as set forth in claim 5 in which said member includes spacedears extending from said second section away from said first section;said pin-slot means including aligned elongated slots in said ears.

'7. A plug as set forth in claim 5 in which said pinslot means includesan elongated slot in said member and a pin mounted to said wall andextending into said slot;

said slot extending generally parallel to said first section.

8. A plug as set forth in claim 1 in which said upper portion includesan additional memberihaving another of said hook portions at one endthereof, additional pinslot means mounting the other end of saidadditional member to'said first wall; said additional pin-slot meansdefining a pivot for said additional member extending generally parallelto said front wall; said additional pinslot means also defining meansguiding said additional member for linear movement toward and away ofsaid another hook portion toward and away from said front wall; anadditional force applying means acting between said housing and saidadditional member for operating the latter to a holding position andholding the additional member at this position.

9. A plug as set forth in claim 8 also comprising an element extendingfrom said side wall into the path of said additional member to restrictpivotal movement thereof.

References Cited by the Examiner UNITED STATES PATENTS 3/1963 Sparkes339-91 ROBERT K. SCHAEFER, Primary Examiner. I

a I. R. SCOTT, Assistant Examiner.

1. A BUST DUCT PLUG COMPRISING A PLURALITY OF BUS BAR ENGAGING FINGERS;A HOUSING TO WHICH SAID FINGERS ARE SECURED; SAID HOUSING HAVING A FRONTWALL WITH AN APERTURE THROUGH WHICH SAID FINGERS EXTEND FORWARDLY OFSAID FRONT WALL; SAID HOUSING ALSO HAVING FIRST AND SECOND END WALLSEXTENDING REARWARDLY FROM OPPOSITE FIRST AND SECOND EDGES, RESPECTIVELY,OF SAID FRONT WALL; MOUNTING MEANS FOR SECURING SAID PLUG TO A BUS DUCTCASING; SAID MOUNTING MEANS INCLUDING UPPER AND LOWER PORTIONS HAVINGINDIVIDUAL OPEN HOOK PORTIONS FACING ONE ANOTHER AND PROJECTING FORWARDOF SAID FRONT WALL; SAID LOWER PORTION INCLUDING A MEMBER HAVING ONE OFSAID HOOK PORTIONS AT ONE END THEREOF, PIN-SLOT MEANS MOUNTING THE OTHEREND OF SAID MEMBER TO SAID FIRST END WALL; SAID PIN-SLOT MEANS DEFININGA PIVOT FOR SAID MEMBER EXTENDING GENERALLY PARALLEL TO SAID FRONT WALL;SAID PIN-SLOT MEANS ALSO DEFINING MEANS GUIDING SAID MEMBER FOR LINEARMOVEMENT OF SAID ONE HOOK PORTION TOWARD AND AWAY FROM SAID FRONT WALL;AN ADJUSTABLE FORCE APPLYING MEANS ACTING BETWEEN SAID HOUSING ANDSECOND MEMBER FOR OPERATING THE LATTER TO A HOLDING POSITION AND HOLDINGTHE MEMBER AT SAID POSITION.